The soul, has grown aware of her obligations and observed that life is short (Job 14:5), the path leading to eternal life constricted (Mt. 7:14), the just one scarcely saved (1 Pet. 4:18), the things of the world vain and deceitful (Eccles. 1:2), that all comes to an end and fails like falling water (2 Sam. 14:14), and that the time is uncertain, the accounting strict, perdition very easy, and salvation very difficult. She knows on the other hand of her immense indebtedness to God for having created her solely for Himself, and that for this she owes Him the service of her whole life; and because He redeemed her solely for Himself she owes Him every response of love. She knows, too, of the thousand other benefits by which she has been obligated to God from before the time of her birth, and that a good part of her life has vanished, that she must render an account of everything—of the beginning of her life as well as the later part—unto the last penny (Mt. 5:25) when God will search Jerusalem with lighted candles (Zeph. 1:12), and that it is already late—and the day far spent (Lk. 24:29)—to remedy so much evil and harm. She feels on the other hand that God is angry and hidden because she desired to forget Him so in the midst of creatures, Touched with dread and interior sorrow of heart over so much loss and danger, renouncing all things, leaving aside all business, and not delaying a day or an hour, with desires and sighs pouring from her heart, wounded now with the love for God, she begins to call her Beloved.  – St. John of the Cross

Msgr. Pope has a beautiful analysis here

St. John of the Cross, pray for us